Cylindrical flatwork ironer

ABSTRACT

The present invention involves a flatwork ironer comprising an ironing cylinder, which is partially surrounded by primary ironing section with an ironing cylinder and at least one primary ironing strip, secondary ironing section with at least one secondary ironing strip, and further comprising a driving section, where the primary ironing section further comprises a compensating item intended to compensate stretch of the primary ironing strip of the primary ironing section, and a pressing item intended to press the pressing cylinder of the primary ironing section to the ironing cylinder, whereas the primary ironing strip is tailored.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119(e) of Czech Patent Application Serial Number PV 2014-547, filed Aug. 15, 2014, the disclosures of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The field of the invention is that of cylindrical flatwork ironers. More particularly, the invention deals with modifications to the ironing sections.

2. Description of the Related Art

A flatwork ironer is a device intended for ironing of flat laundry. A main item of a flatwork ironer is a rotational metal ironing cylinder, advantageously made of steel, with a smooth surface. A hot source intended to heat the ironing cylinder is situated inside of it. The hot source can be a gas burner or an electrical heating coil. For example, the ironing cylinder can be performed as a pressure container if stream heating is used, or as a heat exchanger if oil heating is used.

Around the external surface of the ironing cylinder components of auxiliary cylinders and strip sections are arranged. In general, those sections are arranged in such manner to ensure tight contact of the ironed laundry with the ironing cylinder and to ensure continuous movement of the laundry from a feeding end to an outlet gutter, i.e. in rotary direction of the cylinder.

The construction of the ironing sections of the flatwork ironers is defined by general construction conditions, required for ironing of laundry in required quality:

(a) First condition. High effectiveness of humidity evaporation from the ironed laundry is ensured by pressing of a pressing cylinder of a feeding/primary section to the surface of the ironing cylinder. In other words, the press is situated at the place of the first contact between an ironed laundry and the ironing cylinder. The press has to be ensured by the same constant pressing force at the whole length of the ironing cylinder.

(b) Second condition. High quality of ironing process is ensured if the surface of the pressing cylinder is smooth, because of protection of the ironed laundry from prints caused by protrusions on its surface. The condition is met by smooth high temperature resistant wrap arranged on the pressure cylinder or by a not divided ironing strip surrounding the pressing cylinder.

(c) Third condition. If a strip of the ironing sections with divided ironing strips are used, advantageously connected by hook clips, for example overlapped by aramid protection lapel, which is defined as a protrusion presented on the surface of the ironing strip, nowhere in such section laundry and the ironing strip can't get into the contact, for example by its springing into the free space. If a contact between the laundry and the ironing strip occurs in the area, where on the surface of the ironing strip a protrusion is presented, for example above mentioned aramid lapel, the condition is met, because the ironing strip in such case spring away and the protrusion doesn't left a print on the ironed laundry. The condition is met if the first and the last cylinder of such ironing section is sufficiently removed from the surface of the ironing cylinder. In such case the ironed laundry comes to the contact with the ironing strip sufficiently late behind a lead-in cylinder, where the strip with the protrusion has a possibility to spring out, respectively the ironed laundry coming out from the contact with the ironing strip sufficiently early before a lead-out cylinder, where the strip with a protrusion has still possibility to spring out.

(d) Fourth condition. Speed ratio of single sections has to ensure stretching of the laundry during its transportation from one section to another one in direction to an outlet gutter.

(e) Fifth condition. High effectiveness of evaporation of humidity from the ironed laundry during its transportation below the pressing cylinder of the entry/primary working section is met by shortest length of the primary section. A gap arranged between the end of the primary section and begin of the secondary section, intended for outlet of vapor from the primary section, have to be arranged in the highest place of the flatwork ironer, if possible.

In FIG. 1 is presented a scheme of the first embodiment of the flatwork ironer A100 according to the state of the art, where a primary ironing section A300 is constituted by pressing cylinder A302 with a thermal resistant textile wrap A303, for example made of Nomex® (Nomex is the registered trademark of the E. I. du Pont de Nemours and Company of Wilmington, Del.). The pressing cylinder A302 is accompanied by ribbons A301, which prevent winding of laundry on the pressing cylinder A302. The pressing cylinder A302 of the primary ironing section A300 is permanently pressed towards the ironing cylinder A102.

The primary ironing section A300 is followed by secondary ironing section A400 constituted by secondary ironing strips A401 made of thermal resistant textile, for example made of Nomex®

The wrap A303 on the pressing cylinder A302 of the ironing section A300 has a smooth surface. Because of that it can be pressed to the ironing cylinder A102 without prints left on the ironed laundry. However, the secondary ironing strips A401 are divided due to its length and mounting requirements, and connected by hooked clips overlapped by aramid lapel.

Above mentioned flatwork ironer A100 has a velocity condition: V1<V3<V2<V4, where the velocity V1 is velocity of an entry strip A201, the velocity V2 is velocity of the ironing cylinder A102, the velocity V3 is peripheral velocity of the primary pressing cylinder A302 and the velocity V4 is velocity of the secondary ironing strip A401. Velocity differences V3/V1, V2/V3, V4/V2 and the fact, that a friction coefficient between the laundry and the surface of the ironing cylinder A102 is substantially lower than friction coefficient between the laundry and a textile of the ironing strips A301, A401. Because of that the laundry during its coming through the flatwork ironer A100 is slipping over the surface of the ironing cylinder A102 and its velocity is set by velocity of components of the single sections A300, A400 and by value of pressing force.

In the present case the velocity V4 is about the velocity V2. The peripheral velocity of the pressing cylinder A302 of the primary ironing section A300 have to be reduced with regard to the peripheral velocity V2 of the ironing cylinder A102 to stretch the laundry between the sections A300, A400, and to meet the condition of higher following velocities.

For the presented flatwork ironer A100 the pressing cylinder A302 of the primary ironing section A300 is positioned close to the highest point of the ironing cylinder A102, where pressing created by gravity force of the pressing cylinder A302 is fully used. The pressing force is uniform for the whole length of the pressing cylinder A302.

Such configuration for the primary section meets the first and the second condition, and for the secondary section it meets the third condition and for the whole machine it meets the fourth and fifth condition. However, such performance is possible only in the case, if size of the ironing cylinder A102 ensures a horizontal position of the feeding strips A201 of the entry section A200. An agronomical position of the driving cylinder A202 of the entry section A200 acceptable by operator is another condition. However, such condition is possible only for the flatwork ironer A102, where maximal diameter is approximately 500 mm. When a bigger ironing cylinders A102 are used the reclined entry section A200 has to be used, but the pressing cylinder A302 of the primary ironing section A300 must be moved to the front lower position with regard to the ironing cylinder A102. Because of that, the effect of weight of the pressing cylinder A301 is reduced. Such embodiment is presented in FIG. 1.

If for the presented ironing cylinder A100 a long pressing cylinder A301 is used, which is positioned in the front lower position, bending of the cylinder may occur due to the press effecting only on its edges and not on its center. Because of that, the middle part of the cylinder A302 has no contact with the ironing cylinder, which is a reason of lower pressing force. It has an impact to the quality of ironing. In that case, the primary section A300 of the first embodiment of the flatwork ironer A100 intended for the ironing cylinder A102 with diameter 800 mm doesn't meet the first condition.

In FIG. 2 the scheme of the second embodiment of the flatwork ironer B100 according to the state of the art is presented.

Contrary to the first embodiment of the flatwork ironer A100 the ironing strip B401 of the secondary ironing section B400 of the second embodiment of the flatwork ironer encircles also the pressing cylinder B302, which corresponds to the pressing cylinder A302 of the flatwork ironer A100 according to the first embodiment.

For the flatwork ironer B100 a velocity condition is set as follows: V1<V3<V4, where the velocity V1 is velocity of the entry strip B201, the velocity V2 is velocity of the ironing cylinder B 102 and the velocity V4 is velocity of the ironing strip B401. Such condition ensures to meet the fourth condition of heights subsequent velocities. Because of that the laundry is stretched between subsequent sections A200 and A400.

Because of its length and because mounting conditions has to be ensured the ironing strips B401 are divided and interconnected by hooked clips overlapped by aramid lapel. If the pressing cylinder B302 is stretched by spring and pressed to the ironing cylinder B 102, the clips leave prints on the ironed laundry. The prints of the clips, respectively the aramid lapels, are the main disadvantage of the embodiment influences the quality of the ironing process. The second condition is not met.

In the second embodiment the firm installation of the ironing cylinder B302 is in the sufficient distance from the surface of the ironing cylinder B 102. Such construction ensures to insert the laundry into the contact place of the ironing cylinder B 102 and the ironing strip B401 behind the pressing cylinder B302. In such case the prints on the ironed laundry don't occur. Disadvantage of the second embodiment is a lost effect of the height stroke pressing force, which has a main importance for the quality of the ironed laundry and humidity evaporation. So, the first condition is not met.

Disadvantage of both above mentioned embodiments is, that the construction of the ironing section B400 reduces ability of evaporation of humidity from the ironed laundry occurred in the ironing section B400. It influences quality of ironing. The fifth condition is not met.

In the second embodiment of the flatwork ironer B 100, where the ironing cylinder B102 has diameter 800 mm, the filing cylinder B302 didn't meet neither the first nor the second condition.

The FIG. 3 presents the scheme of the third variation of the flatwork ironer C100 according to the state of the art. It is modification of the second above mentioned embodiment of the flatwork ironer B 100, where one ironing section B400 is divided to two ironing sections C300 and C400. Each of those ironing sections C300 and C400, respectively the ironing strips C301 and C401 of the ironing sections, has its own peripheral velocity. For the flatwork ironer C100 the following velocity condition apply: V1<V2<V3<V4, where the velocity V1 is velocity of the entry strip C201, the velocity V2 is velocity of the ironing cylinder C102, the velocity V3 is velocity of the primary ironing strip C301 and the velocity V4 is velocity of the secondary ironing strip C401. Such condition meet the fourth condition of higher subsequent speeds. Because of that the laundry is permanently stretched between the subsequent sections C200, C300, and C400.

Also in this case, because of its length and because of mounting requirements, the ironing strips of the both ironing sections C300, C400 are preferably divided and interconnected by hooked clips. If the primary pressing cylinder C302 is stretched by not illustrated spring and pressed to the ironing cylinder C102, in the same way as in the first presented embodiment of the flatwork ironer A100, the clips of the ironing strips C301 make prints on the ironed laundry. The prints of the clips pressed to the laundry are main disadvantage of the solution, which has effect on quality of the ironing process. For the section C300 the second condition is met, but for the section C400 the third condition is not met.

Second variety of the above mentioned embodiment of the flatwork ironer C100 has a firmly installed pressing cylinder C302 in sufficient distance from the surface of the ironing cylinder C102. The laundry come to the contact place between the ironing cylinder C102 and the secondary ironing strip C401 behind the primary pressing cylinder C302. In such embodiment the prints don't appear on the ironed laundry. Disadvantage of such embodiment is a lost pressing effect influences quality of ironing and quality of evaporation of humidity. The section C300 doesn't meet the first condition.

In the third variety of the flatwork ironer C100, where ironing cylinder C102 has diameter 800 mm, the input section B300 doesn't meet the first and the second condition at the same time.

The aim of the present invention is to disclose a new type of the flatwork ironer, where above mentioned disadvantages of the state of the art are eliminated, where all conditions are met and the laundry is highest quality ironed.

SUMMARY OF THE INVENTION

The above mentioned disadvantages are considerably eliminated by a flatwork ironer comprises ironing cylinder (102), which is partially surrounded by primary ironing section (300) with an ironing cylinder (302) and at least one primary ironing strip (301), secondary ironing section (400) with at least one secondary ironing strip (401), and further comprises a driving section (500), where the primary ironing section (300) further comprises a compensating item (303) intended to compensate stretch of the primary ironing strip (301) of the primary ironing section (300), and a pressing item intended to press the pressing cylinder (302) of the primary ironing section (300) to the ironing cylinder (102), whereas the primary ironing strip (301) is tailored.

In an advantageous embodiment the pressing item is a spring (307).

In another advantageous embodiment the pressing item is a hydraulic piston.

In another advantageous embodiment the compensating item is a compensating cylinder (303) interconnected to the pressing cylinder (302) by lever (305) with a pin (306).

In another advantageous embodiment the driving section (500) comprises a compensating item (503) intended to compensate stretching of the driving item (501) of the driving section (500), mechanically interconnected to the pressing cylinder (302).

In another advantageous embodiment the compensating item (503) intended to compensate stretching of the driving item (501) of the driving section (500) is a cylinder or a wheel or a pulley.

BRIEF DESCRIPTION OF THE DRAWINGS

The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 presents the schema of the first variant of the ironing section of the flatwork ironer according to the state of the art.

FIG. 2 presents the schema of the second variant of the ironing section of the flatwork ironer according to the state of the art.

FIG. 3 presents the schema of the third variant of the ironing section of the flatwork ironer according to the state of the art.

FIG. 4 presents the schema of the ironing sections of the flatwork ironer according to one embodiment of the invention.

FIG. 5 presents the detail of the primary ironing section of the flatwork ironer according to an embodiment the invention.

FIG. 6 presents the schema of the kinematical system of the driver of the single sections of the flatwork ironer according to an embodiment of the invention.

Corresponding reference characters indicate corresponding parts throughout the several views. Although the drawings represent embodiments of the present invention, the drawings are not necessarily to scale and certain features may be exaggerated in order to better illustrate and explain the present invention. The exemplification set out herein illustrates an embodiment of the invention, in one form, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.

DESCRIPTION OF EMBODIMENTS OF THE PRESENT INVENTION

The embodiments disclosed below is/are not intended to be exhaustive or limit the invention to the precise form disclosed in the following detailed description. Rather, the embodiment is chosen and described so that others skilled in the art may utilize its teachings.

The FIG. 4 presents the flatwork ironer 100 according to the invention with a feeding section 200, a primary ironing section 300 and a secondary ironing section 400, which are interconnected with driver by driving section 500 illustrated in FIG. 6.

The feeding section 200 comprises a feeding strip 201, which surrounds a driving cylinder 202 and a firm edge of an input table not presented in the picture.

The primary ironing section 300 comprises the primary ironing strip 301, which surrounds a pressing cylinder 302, a stretching cylinder 304 and a compensation item, which compensates stretching of a primary ironing strip 301. For example, the compensating item can be a compensating cylinder 303.

The primary ironing strip 301 can by formed by number of parallel strips. Because of short distance of the single strips, each strip is stitched by inclined seam, so prints are not created.

As can be seen in the detail in FIG. 5, the pressing cylinder 302 is interconnected with the compensating cylinder 303 by lever 305 with a firm pin 306 acting as a rotate point. Kinematic of the lever 305 ensures stretching of the primary ironing strip 301 of the primary ironing section 300 during movement of the pressing cylinder 302 and the compensating cylinder 303, during its movement in the Y-direction, when laundry is coming under the pressing cylinder 302, and also during its movement in the backward X-direction, when laundry is leaving the area under the pressing cylinder 302. By that way stretching of the primary ironing strip 301 is constant not influenced by a position of the pressing cylinder 302 and a position of the compensating cylinder 303.

Kinematic of the lever 305 of the feeding section 300 ensures symmetrical press by the strips 301, which surround the pressing cylinder 302 in its whole length. It helps to meet the first condition.

In the present embodiment the levers 305 are two. Each lever 305 is localized on the one end of the pressing cylinder 302, so on the left side of the flatwork ironer and on the right side of the flatwork ironer. Also the springs 307 are two. Each spring 307 is localized on the one end of the pressing cylinder 302, so on the left side of the flatwork ironer and on the right side of the flatwork ironer.

The pressing cylinder 302 is interconnected on both its sides by springs 307 to the frame of the flatwork ironer 100.

The construction of the primary section 300 meets either the first or the second condition.

The secondary ironing section 400 comprises a secondary ironing strip 401, which is constituted by number of parallel strips, which surround five guiding cylinders 402 in this embodiment, and which tightly surround the ironing cylinder 102.

Between the primary ironing section 300 and the secondary ironing section 400 is arranged a gap intended for transfer vapor from the ironed laundry. The gap is arranged in the highest point of the ironing cylinder 102. Through the gap almost 70% of humidity is transferred from the ironed laundry. So, the construction of the primary and the secondary section 300 and 400 meet the fifth condition.

In FIG. 6 the schema of the kinematical driving system of the single sections 200, 300, 400 of the flatwork ironer according to the invention, i.e. driving section 500, is presented. As illustrated in the figure, distribution of a driving force of not illustrated driver is performed by driving items 501, for example by chain. In the mentioned case the driving item 501 is localized on the left side of the flatwork ironer 100. The driving item 501 of the driver in the Z-direction of its movement surrounds the driving cylinder 502 of the driver, the driving cylinder 402 of the flatwork ironer 102, the driving cylinder 302 of the primary ironing section 300, the compensation item 503 to compensate stretch of the driving item 501 of the driving section 500, the driving cylinder 203 of the feeding section 200, the driving cylinder 406 of the secondary ironing section 400, which is in the present embodiment one of the guiding cylinders, and the driving cylinder 504 and 505.

The length of the driving item 501 is independent of the movement of the lever 305.

The compensation item 503 compensates tightening of the driving item 501 of the driving section 500. It is localized on the prolonged part of the swinging lever 305. Because of that the compensating item 503 moves together with the lever 305 around the pin 305 acting as a rotate point. Between the compensation item 503 of the driving section 500 and the pressing cylinder 302 the mechanical connection is created. The compensating item 503 of the driving section 500 can be a cylinder, a wheel or a pulley. Its location is proposed to ensure constant stretching of the driving item 501 during movement of the lever 305. In order to prevent reduction of stretch of the pressing force of the spring 307 because of force in the driving item 501, in the present embodiment length of the lever 305 on the left side, i.e. between the pin 306 and the stretching item 503 of the driving section 500, is lengthened to reach the same pressing force on the pressing cylinder 102 as the spring 307 on the right side of the flatwork ironer 100. Different possibility how to equalize pressing force on the right side and on the left side of the flatwork ironer 100 is a modification of strength of both springs 307.

Apparently, the driving item 501, respectively the whole section 500, can be arranged also on the right side of the flatwork ironer.

In the present embodiment the driving cylinder 203 of the feeding section 200 is localized out of the driving section 200. The driving cylinder 203 is interconnected with the feeding section 200 by the driving item 204, for example by chain.

Mutual ratio of the velocity V1 of the feeding strip 201, the velocity V2 of the driving cylinder 102, the velocity V3 of the primary ironing strip 301 and the velocity V4 of the secondary ironing strip 401 as follows: V1<V2<V3<V4. Differences between those velocities and the fact, that friction between the laundry and the surface of the ironing cylinder 102 is substantially lower than between the laundry and the ironing strips ensures, that the laundry during its coming through the flatwork ironer 100 according to the invention slides over the surface of the ironing cylinder 102 and simultaneously its velocity is preset by velocity of the strips of the single sections 200, 300, and 400 and by value of the corresponding pressing force. The laundry between the following sections is always stretched, so the fourth condition is met.

The process of ironing by the flatwork ironer 100 according to the invention follows:

The front edge of the ironed laundry is before its entry into the primary ironing section 300 shifted by the velocity V1. The pressing cylinder 302 is pressed in the direction X by the pneumatic spring 307 to the ironing cylinder 102. When the front edge of the laundry is shifted by feeding section 200 into the contact area of the ironing cylinder 102 and the primary ironing strip 307, which surrounds the pressing cylinder 302, the pressing cylinder 301 is moved in the Y-direction by the contrary-force of the spring 307. At the time, the laundry is shifted by the speed which is equivalent to the velocity of the ironing strip 301 of the primary ironing section 300. Because of that, stretching caused by higher following speed is ensured.

Advantageous of the above mentioned embodiment of the primary and the secondary ironing section, respectively of the gap localized between the primary and the secondary section in the high point of the flatwork ironer follows:

-   -   the construction of the kinematical entry section 300, which is         characterized by optimized geometry of movement, ensures ability         to use closed tailored strips 301 with the length, which is not         influenced by movement of the lever 305,     -   the construction of the kinematical entry section 300         characterized by optimized geometry of movement ensures         possibility to use a driving item 500 of length, which is not         influenced by movement of the lever 305,     -   short length of the primary ironing strip 301 ensures ability to         use the continual closed strip 301 without hooked clips. Because         of that the second condition is met, because of that press of         the pressing cylinder 302 by the pressing item to the ironing         cylinder 102 is complied, so the first condition is met,     -   working length of the feeding section is long enough to arrange         the gap between the primary and the secondary section in an         optimal position, which influences the quality of the transfer         of vapor occurred during laundry ironing in the primary ironing         section. Because of that the fifth condition is met.     -   lengthening of the secondary ironing section 400, which meet         also the third condition, lengthens the final ironing process         and helps to spit uniformly press over the whole length of the         ironing cylinder 102,     -   shortening of the primary ironing section 300 ensures better use         of the effect of pulse pressing.

While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains. 

What is claimed is:
 1. A flatwork ironer comprises ironing cylinder, which is partially surrounded by primary ironing section with an ironing cylinder and at least one primary ironing strip, secondary ironing section with at least one secondary ironing strip, and further comprises a driving section characterized in that the primary ironing section further comprises a compensating item intended to compensate stretch of the primary ironing strip of the primary ironing section, and a pressing item intended to press the pressing cylinder of the primary ironing section to the ironing cylinder, whereas the primary ironing strip is tailored.
 2. A flatwork ironer according to the claim 1 characterized in that the pressing item is a spring.
 3. A flatwork ironer according to the claim 1 characterized in that the pressing item is a hydraulic piston.
 4. A flatwork ironer according to the claim 1 characterized in that the compensating item is a compensating cylinder interconnected to the pressing cylinder by a lever with a pin.
 5. A flatwork ironer according to the claim 1 characterized in that the driving section comprises a compensating item intended to compensate stretching of the driving item of the driving section, mechanically interconnected to the pressing cylinder.
 6. A flatwork ironer according to the claim 1 characterized in that the compensating item intended to compensate stretching of the driving item of the driving section is a cylinder or a wheel or a pulley.
 7. A flatwork ironer comprising: an ironing cylinder, which is partially surrounded by a primary ironing section with an ironing cylinder and at least one primary ironing strip, the primary ironing section further comprising a compensating item intended to compensate stretch of the primary ironing strip of the primary ironing section, and a pressing item intended to press a pressing cylinder of the primary ironing section to the ironing cylinder, the primary ironing strip being tailored; a secondary ironing section with at least one secondary ironing strip; and a driving section.
 8. A flatwork ironer according to the claim 7 characterized in that the pressing item is a spring.
 9. A flatwork ironer according to the claim 7 characterized in that the pressing item is a hydraulic piston.
 10. A flatwork ironer according to the claim 7 characterized in that the compensating item is a compensating cylinder interconnected to the pressing cylinder by a lever with a pin.
 11. A flatwork ironer according to the claim 7 characterized in that the driving section comprises a compensating item intended to compensate stretching of the driving item of the driving section, mechanically interconnected to the pressing cylinder.
 12. A flatwork ironer according to the claim 7 characterized in that the compensating item intended to compensate stretching of the driving item of the driving section is a cylinder or a wheel or a pulley.
 13. A flatwork ironer comprising: an ironing cylinder, which is partially surrounded by a primary ironing section with an ironing cylinder and at least one primary ironing strip, the primary ironing section further comprising compensating means for compensating for the stretch of the primary ironing strip of the primary ironing section, and pressing means for pressing a pressing cylinder of the primary ironing section to the ironing cylinder, the primary ironing strip being tailored; a secondary ironing section with at least one secondary ironing strip; and a driving section.
 14. A flatwork ironer according to the claim 13 characterized in that the pressing means includes a spring.
 15. A flatwork ironer according to the claim 13 characterized in that the pressing means includes a hydraulic piston.
 16. A flatwork ironer according to the claim 13 characterized in that the compensating means includes a compensating cylinder interconnected to the pressing cylinder by a lever with a pin.
 17. A flatwork ironer according to the claim 13 characterized in that the driving section comprises a compensating item intended to compensate stretching of the driving item of the driving section, mechanically interconnected to the pressing cylinder.
 18. A flatwork ironer according to the claim 13 characterized in that the compensating means for compensating for stretching of the driving item of the driving section includes at least one of a cylinder or a wheel or a pulley. 